Re: pxa_defconfig runtime failures due to 'ARM: pxa: activate pinctrl for device-tree machines'

[Guenter Roeck]

On 05/28/2016 01:24 AM, Robert Jarzmik wrote:
> Guenter Roeck <linux@xxxxxxxxxxxx> writes:
>
> > Hi,
> >
> > your mainline commit f806dac5938b ("ARM: pxa: activate pinctrl for device-tree
> > machines") causes various non-devicetree systems to fail with the following
> > error messages when running a pxa_defconfig image.
> Ah yes, you're right.
>
> > During boot:
> >
> > Can't request reset_gpio
> >
> > At reboot:
> >
> > reboot: Restarting system
> > ------------[ cut here ]------------
> > kernel BUG at arch/arm/mach-pxa/reset.c:59!
> > ...
> >
> > Added logging shows that the error seen when trying to request the reset gpio
> > is -EPROBE_DEFER, and that the pxa gpio driver is not instantiated.
> >
> > This is seen when attempting to run akita, borzoi, spitz, terrier, or tosa
> > in qemu with pxa_defconfig. Reverting your patch fixes the problem.
> >
> > Is this on purpose ?
> Well no :)
> The real reason behind is that gpio handling for pxa in its current state cannot
> be built for _both_ a devicetree machine (ie. pxa-dt.c) and a non devicetree
> machine (ie. corgi, tosa, ...).
>
> This is turn is because for devicetree a pinctrl is enforced for the machine,
> and a pinctrl driver is required. If it's not available, pxa_gpio_request()
> fails on pinctrl_request_gpio() and returns -EPROBE_DEFER.
>
> Now the true chicken and egg problem is than machine files,
> ie. arch/arm/mach-pxa/xxx.c are using gpio before the drivers are probed, in the
> init_machine() function, and that's why pinctrl/gpio for legacy machine files is
> a bit difficult.
>
> > Unless I am missing something, it effectively means that
> > pxa_defconfig no longer works for pxa3xx systems, since those do not support
> > devicetree (or at least there is no devicetree file which includes
> > pxa3xx.dtsi).
> I'd rather say that pxa_defconfig doesn't work anymore on any legacy system.
> Its first purpose was to ensure compilation coverage of all legacy pxa systems.
> Its second one was to have a single kernel bootable on all legacy pxa systems.
>
> Therefore, would you tell me if the patch in [1] fixes your issue ?

Yes, it does. It is actually the workaround I deployed for my test builds,
since I thought that the change was on purpose.

Thanks,
Guenter